Math calculator
Combination Calculator
Calculate C(n,r): selections where order doesn't matter.
About the combination calculator
The combination calculator finds C(n,r): the number of ways to choose r items from n where order doesn't matter.
How to use this calculator
- 1
Enter n and r
Enter the total items (n) and items chosen (r).
- 2
View results
See the number of combinations.
How the calculation works
C(n,r) = n! ÷ (r! × (n−r)!). Order doesn't matter.
Example: C(5,3) = 10.
When to use a calculator vs. mental math
Simple operations like percentages and proportions are great for mental math. Complex problems — quadratic equations, standard deviation, and base conversions — benefit from calculator precision. Always estimate the answer first to catch input errors, and verify results with a second method when possible.
Important limitations
This tool provides a mathematical estimate based only on the values entered. It does not account for regulations, taxes, lender fees, market conditions, or individual circumstances. Results are for planning purposes only — consult a qualified professional for regulated, medical, financial, or construction decisions.
Frequently asked questions about combination calculator
How accurate is the combination calculator?+
The calculation follows the displayed formula and retains full numeric precision before formatting the result.
Can I use the result professionally?+
Use it as a planning estimate. Confirm regulated, medical, financial, or construction decisions with a qualified professional.